A room temperature curable composition which cures an elastomer state at room temperature by a condensation and crosslinking reaction from contact with the moisture in the air, particularly a room temperature-curable organopolysiloxane composition has conventionally been known in various types of materials, and above all, a material of the type which cures by discharging alcohol is preferably used for sealing, adhesion or coating of an electric and electronic devices, etc., due to its characteristics that there is no unpleasant smell and it does not corrode metals.
As representative example of such a type, a room temperature-curable organopolysiloxane composition comprising a polyorganosiloxane the terminal of which has been blocked by a hydroxyl group, an alkoxysilane and an organotitanium compound; a room temperature-curable organopolysiloxane composition comprising a polyorganosiloxane the terminal of which has been blocked by an alkoxysilyl, an alkoxysilane and an alkoxytitanium; a room temperature-curable organopolysiloxane composition comprising a linear polyorganosiloxane the terminal of which has been blocked by an alkoxysilyl group containing a silethylene group, an alkoxysilane and an alkoxytitanium; and a room temperature-curable organopolysiloxane composition comprising a polyorganosiloxane the terminal of which has been blocked by a hydroxyl group or a polyorganosiloxane the terminal of which has been blocked by an alkoxy group and an alkoxy-α-silyl ester compound have been disclosed (Patent Literatures 1 to 4).
These compositions are advantageously employed in view of a certain level of storage stability, water resistance, and humidity resistance. However, these problems have not been completely solved yet. Further, they were insufficient with regard to rapid curability.
As described above, a polymer having a reactive alkoxysilyl group has conventionally been known. The terminal group of this polymer has previously been blocked by an alkoxysilyl group, so that curability of the polymer difficultly change (lower) with a lapse of time, and a composition that is excellent in storage stability can be obtained. Also, workability (viscosity and thixotropic property) thereof can be optionally adjustable, and it reacts with a moisture in the air to form an elastomer by crosslinking, whereby excellent characteristics (hardness, tensile strength and elongation at break) can be also obtained.
However, a dealcoholization type of room temperature-curable organopolysiloxane composition comprising an organosiloxane polymer having such a reactive alkoxysilyl group at its terminal as a main agent (a base polymer) was insufficient in curability as compared to the other conventionally known curing types such as a deoximation type, a deacetylation type, a deacetone type, etc., since reactivity with a moisture in the air is low.
In response thereto, researches focused on a functional group (a bonding group) adjacent to the reactive alkoxy group have been promoted, and it has been reported that an α-alkoxysilylmethyl terminal group has particularly high reactivity with a moisture in the air (Patent Literature 5). However, curability thereof is yet insufficient, and there are defects that the adjacent functional group (a bonding group) exerts bad effect to durability, and a restoring force of the cured product is low.